I work remotely and report my hours online every two weeks, then receive a paycheck based on what I report. I would like to report my hours with better accuracy so I decided to create a work account on my MBA so every night I can log in to that account and do solely hourly work. Is there any automator script I could write or free 3rd party applications I could use to easily track and report the length of time I was logged into my work account every two weeks?

DESCRIPTION
Last will list the sessions of specified users, ttys, and hosts, in
reverse time order. Each line of output contains the user name, the tty
from which the session was conducted, any hostname, the start and stop
times for the session, and the duration of the session. If the session
is still continuing or was cut short by a crash or shutdown, last will so
indicate.